Solid silicic acid containing bleaching agents and process of making the same



Patented Dec, 29, 1931 UNITED STATES,

PATENT OFFICE h JOHN D. HASEMAN, OF LINTON, INDIANA SOLID SILICIC ACID CONTAINING BLEACHING AGENTS AND PROCESS OF MAKING THE SAME No Drawing.

This invention relates to bleaching agents and particularly to solid silicic acid containing bleaching agents of the general nature of fullers earth and other silicon containing bleaching earths now used in removing color from animal, vegetable and mineral Oils.

My invention is chiefly concerned with activated silica or more exactly, solid silicic acid or acids having unusual bleaching efficiency which may be transformed into inactive silica by removing the combined water contained therein, as by being heated to a very high temperature.

I have discovered that a. solid silicic acid containing bleaching agent having very high bleaching efficiency and low oil retaining capacity can be readily and satisfactorily ob- 'tained from indianite, halloysitc, bentonite and other clays or clay-like earths which upon the addition of a mineral acid such as I have discovered that my improved solid silicic acid containing bleaching agent can be obtained from alkali metal silicates such as water glass. by treatment with a mineral acid such as sulfuric acid, washing the solid product obtained and heating it to remove the free water and a part but not all of the combined water.

I also have discovered that silicic acid containing solid bleaching agents of the charac- 49 ter now in use as well as the improved prodnot produced in accordance with my invention are rendered materially more efiicient in their bleaching action if used in association with and preferably in intimate mixture with alumina and by this term as used herein I mean to include both aluminum oXid and aluminum hydroxid as both may be used to serve the purpose stated.

I also have discovered that fullers earth 50 and other bleaching earths now in use for re- Serial No. 140,422.

moving color from animal, vegetable and mineral oils can be materially improved with respect to their bleaching activity and at the same time so modified as to retain less of the oil treated therewith by diminishing the porosity of such solid bleaching materials as by wholly or in part sealing or stopping up their pores by depositing on the surface of such material and within their pores colloidal material preferably my silicic acid containing solid bleaching agent and more particularly such agent obtained from an alkali metal silicate as hereinbefore referred to and with which bleaching agent is prefer-' ably associated a relatively small amount of alumina.

In the practice of my invention based upon the discoveries referred to I treat indianite, halloysite, bentonite or other clays or claylike earths which upon the addition of mineral acid, such as sulfuric acid, yield a substantial amount of a soluble aluminum salt or salts of such acid, with a mineral acid, preferably sulfuric acid, and remove the resulting solution of the soluble aluminum salt or salts produced. The residue is then washed substantially free from acid and other soluble impurities and heated to a temperature sufiicient to drive off all of the free water and apart of the combined water.

In the preferred treatment of indianite, I

mix approxin'iately 925 pounds of commer-- cial sulfuric acid of approximately 90 per cent. strength with 1,850 pounds of water and to the resulting diluted sulfuric acid I add 1,000 pounds of indianite, preferably ground to from 20 to 100 mesh. The mixture is heated to about its boiling point for from one-half to five hours preferably under ordinary conditions for about one hour and a half and the resulting solution of soluble aluminum salts consisting chiefly of alum separated from the residue by decantation, filtration or otherwise. The alum may be removed from the solution as by crystallization, separated from the impurities present as by recrystallization and marketed. The

residue remaining after the separation of the solution of the soluble aluminum salt or salts is then washed with water until substantially acid free and heated to remove the free water and part of the combined water present therein. In practice I slowly raise the temperature of the residue to a dull red heat, such heat serving to drive off all of the free water resent and a part but not all of the comiiined water. I prefer to remove about half of the combined water. The material is then allowed to cool and ground to a degree of fineness depending upon the character of the bleaching process in which the material is to be used. If the material is to be employed for bleaching by the filtration method, which is commonl used in bleaching animal and vegetable OllS, I prefer to grind the material to about 200 mesh. 'If the material is to be employed for bleaching by the percolation method, which is commonly used in the bleaching of mineral oils, the' material is preferably ground to from 20 to mesh. It may be produced in much coarser form if desired.

In the preferred practice of preparing my bleaching agent from halloysite I first mix 1,400 pounds of sulfuric acid with 2,800 pounds of water and to this I add 1,000 pounds of halloysite preferably ground to from 20 to 60 mesh. The mixture is allowed to boil slowly for preferably about one hour and a half and the resulting solution of soluble aluminum salts consisting principally of alum removed by decantation or otherwise. The alum may e separated, purified and sold. The residue is then washed substantially acid free and slowly heated to a dull red heat as described above.

In the preferred treatment of bentonite I preferably mix 400 pounds of commercial sulfuric acid with 800 pounds of water and to this I add 1,000 pounds of bentonite preferably ground to 20 to 100 mesh. I then boil the material for preferably about one hour and a half. The resulting solution which contains aluminum sulfate, iron sulfate and other soluble salts, is removed by decantation or otherwise and the residue washed and heated to a dull red heat as set forth above. In each case I prefer to drive off only about one-half of the combined water present.

Indianite, halloysite, bentonite and other clays or clay-like earths of the character hereinbefore referred to ordinarily contain some aluminum in the form of oxid or hydroxid, generally the latter, and in treating these materials I preferably add in each case an insufficient quantity of the sulfuric acid to transform all of the aluminum oxid or hydroxid present into aluminum sulfate. I preferably employ the sulfuric acid in such proportion with respect to the material under treatment that there remains in the residue from 2 to 10 per cent. of the aluminum oxid or hydroxid. My product ordinarily contains about 5 per cent. of alumina but it may contain a much smaller or larger proportion of alumina. I may produce a satisfactory bleaching agent by the use of such an amount of the mineral acid as to dissolve and remove all of the aluminum oxid or hydroxid present but the product thus produced, being free from alumina, is not as eliicient a bleaching agent as the product is when it contains a relatively small proportion of the almninum oxid or hydroxid. The presence of the alumina materially improves the bleaching elliciency of the product.

I can satisfactorily produce my solid silicic acid containing bleaching agent by mixing commercial water glass of the strength commonly used in egg preservation, of specific gravity approximately 1.7, with aluminum hydroxid in the preferred proportion of 1,000 pounds of sodium silicate to 150 ounds of soluble aluminum hydroxid and adding thereto preferably 800 pounds of dilute sulfuric acid produced by mixing 320 pounds of commercial sulfuric acid with 480 pounds of water. The mixture is boiled for about one hour and a half and the solution of aluminum and sodium salts removed by decantation or otherwise. The residue is then washed substantially acid free and slowly heated to a dull red heat to drive off the free water and a part of the combined water as hereinbefore explained. The resulting solid product is then ground to the desired degree of fineness depending upon the bleaching process in which the material is to be used.

In place of using sodium silicate as described above I may produce my improved bleaching agent by treating 1,000 pounds of high grade kaolin such, for example, as the American Kaolin Companys Georgia kaolin, with 500 pounds of commercial sodium bydroxid of about 96 per cent. strength dissolved in 3,300 pounds of water. This mixture is boiled for preferably one and one-half hours. To the resulting product I add 1,500 pounds of commercial sulfuric acid and boil for about one and one-half hours. The resulting solid product is then separated from the solution by decantation, filtration or the like and thoroughly Washed with water until it is substantially acid free. It is dried by slowly heating-t0 a dull red heat, care being taken not to heat the material above this point. The dry product is finely ground to a degree of fineness depending upon the bleaching process for which it is to be used as explained above.

The bleaching material produced by my process as above set forth is a silicic acid containing solid bleaching agent bearing it is thought substantially the same relation to silica which activated carbon bears to ordinary carbon. It is with absolute conviction believed to be solid silicic acid or a mixture of silicic acids.

In the practice of my process care must be 1,888,621 Y c 4 O taken to prevent the bleaching properties of ower is to a certain extent destroyed and 1f heated to a white heat its bleaching'power is entirel destroyed. This is believed to be due to ecomposition of the silicic acid or acids at the hi h temperatures referred, to.

The removal all of the water of constitution from the material reduces it to silica and destroys its bleaching capacity.

- mixture of'such aclds, alt

Theoretically there are monosilicic acid, disilicic acid and trisilicic acid as the salts of such acids are known. I have been unable to determine whether or not the silicic acid which I roduce is the monosilicic acid, disilicic acid or the trisilicic acid, but it is believed that all of these silicic acids are produced in my process with the disilicic acid forming by far the greater. proportionpf the ough it may be that only the disilicicacid is produced.

The bleaching power of fullers earth or other silicon containing bleaching agent is substantially in proportion to its relative acidity. My composition produced as above described has a relative acidity which is more than twice that of the best fullers earth now in use, as, for exam le, what is known in the trade as Floridian XF fullers earth. Its

bleaching power is more than double that of Floridian XXF fullers earth. The material also differs greatly from fullers earth and other bleaching earths with respect to 0- rosity. Its pores are finer and of materia lly less volume than the pores of fullers earth,

its absorbing capacity for oil being at least 50 per cent. less than that of fullers earth. In consequence of its lesser degree of orosi't it retains at least 50 percent. less 0 the Oll bleached therewith. Its use therefore has the advantage that a given quantity of it' will bleach to standard color two orthre times as much oil as can be so bleached by a corresponding weight of fullers earth and the retention of oilas indicated above is at least 50 percent. less, whereby an important economy in the bleaching of oil is obtained.

I have found that my improved silicic acid containing bleaching material can be deposited u on and to some extent within the pores of ullers, earth and other similar silicon containing bleaching earths thereby increasing the bleaching activity of such bleaching earth and lessening its retention of oil bleached therewith. In the preferred practice of this modification of my invention I add to 1,000 pounds of commercial fullers earth approximately 1,000 pounds of commercial sodium silicate (water glass) of the strength commonly used in egg preservation and about 500 pounds of water to which may advantageously be added about pounds 'oughly mixing with 1,000

of aluminum hydroxid. The materials are then thoroughly mixed and boiled for about one hour. 0 this mixture I then add 500 pounds of commercial sulfuric acid and boil for about one hour and a half. The first boiling operation can be omitted, but I have found in practice that such boiling is an efficient way of depositing my material upon the surface of and within the pores of the fullers earth. The second boiling operation is, however, necessary in order to produce my silicic acid containing bleachin agent upon and within the bleachin eart The fullers earth or the like treate as above described is allowed to cool and is thoroughly washed and dried. The drying operation isperformed in the manner above described by slowly heating to a dull red heat to remove the free water and a part of the combined water, care being taken to avoid heating to matreated fullers earth. If the alumina is added, as is preferred, the bleaching efiiciency of the product is still further enhanced.

The product produced in the manner last described has not as great oil bleaching efiiciency as my activated silica or silicic acid or acids employed alone but is superior in bleaching efiiciency to the best fullers earth obtainable and is adapted for economical commercial use.

I may with some degree of practical success wholly or partially seal or stop up the pores of fullers earth or like bleaching earths otherwise than in the manner described. I have found that the pores of such earths may to a considerable extent be sealed by thorpounds of such earth, preferably high grade fullers earth, a mixture or suspensionof 30 pounds of kaolin, preferably of the grade known in the trade as American Kaolin Companys Georgia kaolin, in 5,000 pounds of water. The kaolin suspended in the water is to a considerable extent absorbed in the fullers earth and the pores thereofare sealed or stopped upto a considerable extent. The thus treated fullers earth is heated to evaporate the water present and preferably slowly heated to a dull red heat to drive oil the free water and a part but not all of the combined water. The product thus obtained has increased bleaching, efficiency as compared with the original fullers earth and retains less of the oil bleached therewith.

While I have described in detail the various embodiments of my invention and the preferred processes employed in producing the same itis to beunderstood that my invention is not restricted to the proportions parts by wei ht of water and 1,000

of ingredients, details of procedure, and the like except as set forth in the appended claims.

This application is in part a continuation of my copending application Serial No. 713,630, filed May 15th, 1924, for fullers earths and certain other clays and siliceous materials, as to the common subject matter set forth in the five paragraphs immediately preceding.

My composition while primarily intended for bleaching purposes has been found to be particularly well adapted for use in absorbing or taking up gasoline and other volatile hydrocarbons from natural gas. When intended for such use the com osition need not be finely ground but may a vantageously be in the form of coarse granules or it may be formed into small cubes, or other shapes. In making this use of my composition the gas is passed through the material until a considerable quantity of the volatile hydrocarbons have been taken up. heated to about 200 C. or above to drive off hydrocarbons thus taken up and the vapors condensed. The composition after the removal of the hydrocarbons is ready for reuse.

I claim:

1. The herein described rocess compris ing reacting upon silicic aci containing claylike earths normally containing aluminum oxid or hydroxid and which upon treatment with sulfuric acid yield a substantial amount" The material is then of a deposit comprising an intimate mixture of alumina. and a solid silicic acid-containing compound which normally contains water of constitution but containing less than its nor mal content of such water.

5. A bleaching material comprising a fullers earth having its pores diminished by the presence of a deposit comprising an intimate association of alumina and a solid silicic acid-containing compound which normally contains water of constitution but containing less than its normal content of such water.

6. The herein described process which comprises subjecting a silicic acid-containin compound which normally contains water 0 constitution and is reducible to inert silica upon being heated to a white heat, to a suflicient temperature to remove a part but not all of its combined water, and reducing the thus treated silicic acid-containing compound in admixture with alumina to a finely divided condition.

7. The herein described process comprising subjectin asilicic acid-containing compound norma ly containing water of constitution and reducible to inert silica upon being heated to a white heat, to a sufliclent temperature to remove a part but not all of its combined water, mixing alumina with the resulting roduct, and grinding the mixture to finely ivided condition.

In testimony whereof I afiix my signature.

. JOHN D. HASEMAN.

acid in such amount as to dissolve a part but not all of the aluminum oxid or hydroxid present, removin the resulting aluminum salt solution, was in the residue, heating it to a temperature su cient to remove a part but not all of the combined water present therein and grinding the product to powdered form. n

3. The herein described process comprising mixing dilute sulfuric acid and powdered indianite in the approximate proportions of 810 parts by weight of sulfuric acid, 1,9:0

rts weight of indianite, boiling the solutlon, sep arating the resulting solution of alum and other salts, washing the residue until substantially free from acid, heating the residue to a dull red heat, and grinding the product. 

